text: Consider a fluid mass  of volume  with density  and an isotropic pressure  with vanishing pressure at the bounding surfaces. Here,  refers to a frame of reference attached to the center of mass. Before describing the virial equations, let's define some moments.
  The density moments are defined as
  the pressure moments are
  the kinetic energy moments are
  and the Chandrasekhar potential energy tensor moments are
  where  is the gravitational constant.
  All the tensors are symmetric by definition. The moment of inertia , kinetic energy  and the potential energy  are just traces of the following tensors
  Chandrasekhar assumed that the fluid mass is subjected to pressure force and its own gravitational force, then the Euler equations is